The invention relates generally to apparatus for producing a skin incision in order to cause bleeding and to a method for making such apparatus, and more particularly to a disposable finger stick device capable of producing an incision.
Blood samples are drawn routinely from patients for use in various types of blood tests. The blood is usually taken from an appropriate area, such as the patient's fingertip. A series of mechanical devices for producing skin incisions necessary to draw blood samples have been developed. One such device is a reusable mechanical device that has a disposable blade. To its advantage, the mechanical device prevents the patient from seeing the often unsettling scene of his skin being cut. Further, the mechanical device provides good control of the incision. However, handling of the blades during disposal presents a danger. There is the danger of being cut by the exposed edge. Further, the health problems posed by used blades are apparent. More recent health considerations, including the possibility of contracting the AIDS virus from disposed blades, have increased the need for safer devices.
Disposable devices that produce standardized skin incisions were developed to overcome the problem caused by disposable blades. For instance, the device disclosed in U.S. Pat. No. 4,078,552, entitled "DEVICE FOR AND METHOD OF MAKING STANDARD AND REPRODUCIBLE SKIN PUNCTURES", issued to Evan N. Chen on 14 Mar. 1978 and assigned to Warner-Lambert Company, has a housing and a blade located inside the housing. The blade is supported by a post, which is surrounded by a spring. When a release mechanism associated with the housing is activated, the spring pushes the blade in a downward thrust, much like the action of a guillotine, and hence the blade penetrates the patient's skin, thereby making a puncture. The blade is not retractable, which causes two major drawbacks. First, the blade, once activated to penetrate the skin of a patient, remains within the patient's skin until the housing is pulled away. Therefore, the blade is in the patient's skin for a period longer than necessary, thereby causing unnecessary pain. Second, the blade, once removed from the patient's skin, is still exposed to the technician and patient, and therefore presents the same handling and health problems indicated above.
The "LANCET" disclosed in U.S. Pat. No. 4,677,979, issued to James Burns on 7 Jul. 1987 and assigned to Becton, Dickson and Company, has essentially the same structure as the device disclosed in the Chen reference, the difference being that the release mechanism includes a plunger that depresses the spring-like mechanism, and that a resilient member is located between the plunger and the housing. When the plunger is released, the resilient member forces the plunger upwards, causing the blade to be removed from the patient's skin and withdrawn into the housing. However, the problem relating to the exposed blade is not entirely overcome, since the plunger can be reactuated and the blade can be directed from the housing again. This operation can cause a contaminated blade to be inserted into the skin of another person. Furthermore, the problem attributed to unnecessary pain is not overcome, since the blade is not removed from the patient' skin until the plunger is released.
U.S. Pat. No. 4,735,203, entitled "RETRACTABLE LANCET", issued to Francis E. Ryder and Harold L. Purdy on 5 Apr. 1988 and assigned to Ryder International Corporation, appears to avoid that problem. The RETRACTABLE LANCET includes a housing having an open end, a carrier, which is mounted in the housing for a sliding motion toward and away from the open end, and a blade which is affixed to a carrier. A resilient biasing member is mounted in the housing in a prestressed condition and is operatively coupled for selectively urging the carrier toward and away from the housing open end. A non-resettable release member normally retains the biasing member in its prestressed condition and is selectively activated for releasing the resilient bias member, which sets the carrier into motion. The cutting edge of the blade is projected through the opening and makes a downward thrust which punctures the patient's skin. Immediately following the downward thrust is a movement which includes a retraction of the entire blade into the housing. Thus, the blade performs the incision and then is retracted back into the housing to enable safe disposal of the unit.
Essentially, the incisions produced by the above-noted prior art devices are made by a downward thrust into the skin. Further, there may be a problem of excessive force being applied to the skin, which can cause skin tissue to be damaged. Generally, only a small amount of downward force is required to make the incision. However, when the operator actuates the device, his hand may exert an additional, and often excessive, downward force. Thus, the guillotine-like, vertical thrust of the blade, coupled with excessive downward force exerted by the operator may cause damage to the skin and cause skin tissue juices to mix with blood. This mixing provides improper blood samples.
The "APPARATUS FOR IMPLEMENTING A STANDARDIZED SKIN INCISION" disclosed in U.S. Pat. No. 4,643,189, issued to Michael Mintz on 17 Feb. 1987 and assigned to W.T. Associates, includes a housing having an internal hollow and a base containing an elongated slot. The internal hollow contains a movable pivot arm having a first pivotal end and a second end having a cam follower. There is a cam surface upon which the cam follower of the pivot arm rides. The pivotal end of the arm includes a cutting edge, which moves transversely while the arm is pivoting. The cam controls the path of the cutting edge as it enters the slot. After the unit is triggered, the edge projects through the slot in the housing along a given path to implement the incision. After traversing the path, the cutting edge is withdrawn into the housing to prevent further use and injury. Thus, this retractable-disposable device has a rapid action that produces a scalpel-like incision of standard length. Furthermore, the device is fabricated from molded plastic and simple metal parts, which makes manufacture simple and economical.
It is an objective of the present invention to provide a reliable and safe device that produces a predetermined incision and that can operated with minimum effort.
It is a further objective of the present invention to provide a method of manufacturing such a device at a reasonable cost.